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The City of Cape Town is not required to provide "an uninterrupted supply" of water to residents, mayoral committee member Water and Waste Services Xanthea Limberg said.

Limberg said according to the water by-law, the city does not "constitute an undertaking to maintain at any time or at any point in its water supply system".

This included maintaining a specific water pressure.

Limberg was responding to questions from News24 over concerns raised that the city's advanced water pressure reduction scheme could permanently damage solar powered geysers.

During advanced water pressure reduction, residents in high lying areas can expect disruptions to water supply during peak consumption in the mornings between 05:00 and 09:00, and in the evenings between 17:00 and 21:00.

Thermal shock

Limberg said high-pressure solar water geysers should be able to withstand a few days without water with no adverse effect on the panel, geyser or pump.

"If water outages are expected to last longer than a week, the city advises customers to cover the panel with reflective sheeting or a dark tarpaulin."

Water outages are expected to only last a number of hours and not days or weeks, Limberg added.

She said that low-pressure evacuated tube systems, which are predominantly installed in low-income households, are at risk when the geyser is completely emptied.

The tubes of the geyser can be damaged when it experiences thermal shock.

Limberg advised residents with low-pressure tube systems to cover the panel with a dark blanket or reflective sheeting and disconnect water to the geyser until the water supply is restored.

Arno van Wyk, managing director at solar heating supplier MrSola, agreed and said no solar geysers, which comply with the South African National Standards (SANS), would burst or explode as a result of prolonged water outages.

"Electrical geysers are also only at risk of burning out their element if they are completely empty," Van Wyk said.

Professor Thinus Booysen from Stellenbosch University's electrical and electronic engineering department previously told News24 that solar water geysers are dependent on cold water to regulate temperatures.

He said if water in the panel becomes too hot, or pressure too high, the safety valve opens which replaces hot water with cold water.

"In the event of a water outage, no cold water will replace the hot water, which could lead to overheating, and which could result in scalding (when hot water is used and it is beyond 100°C), and the solar system possibly stalling, which in turn could lead to permanent damage," Booysen said.